La0.5Sr0.5MnO3　films　on　(001)　LaAlO3　were　prepared　by　RF　magnetron　sputtering　using　powder　target　and　were　studied　by　SQUID　and　XPS.　The　XPS　results　show　the　formation　of　Mn3+　and　Mn4+,　indicating　the　coexistence　of　ferromagnetic　(FM)　and　antiferromagnetic　(AFM)　clusters.　SQUID　measurement　of　LSMO　on　LAO　and　Si　also　support　an　interaction　between　them　at　low　temperatures,　resulting　in　the　shift　of　hysteresis　loops.　Large　coercivities　at　low　temperature　can　be　attributed　to　the　pinning　of　both　FM　and　AFM　clusters　and　small　coercivities　at　high　temperature　to　the　depinning　of　both　FM　and　AFM　phases,　resulting　from　the　thermal　motion　at　higher　temperatures　which　help　to　overcome　the　energy　barrier　and　change　the　magnetic　alignments.